{"id":54312,"date":"2019-12-23T00:00:00","date_gmt":"2019-12-22T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/kak-rabotaet-videokodek-chast-1-osnovy"},"modified":"2020-02-18T14:02:18","modified_gmt":"2020-02-18T11:02:18","slug":"kak-rabotaet-videokodek-chast-1-osnovy","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/news\/kak-rabotaet-videokodek-chast-1-osnovy","title":{"rendered":"Si funksionon kodeku video. Pjesa 1. Bazat","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Pjesa e dyt\u00eb: Parimet e funksionimit t\u00eb videokodek\u00ebve<\/a><\/noindex><\/h3>\n

Cdo pamje raster mund t\u00eb paraqitet si<\/b> nj\u00eb matric\u00eb dy-dimensional\u00eb . Kur flasim p\u00ebr ngjyrat, ideja mund t\u00eb zhvillohet duke shqyrtuar pamjen si<\/b>nj\u00eb matric\u00eb tre-dimensional\u00eb , ku dimensionet shtes\u00eb p\u00ebrdoren p\u00ebr t\u00eb ruajtur t\u00eb dh\u00ebna p\u00ebr secil\u00ebn nga ngjyrat.<\/b>N\u00ebse e shqyrtojm\u00eb ngjyr\u00ebn p\u00ebrfundimtare si nj\u00eb kombinim t\u00eb ngjyrave kryesore (e kuqe, e gjelb\u00ebr dhe e azul), n\u00eb matric\u00ebn ton\u00eb tre-dimensional\u00eb p\u00ebrcaktojm\u00eb tre plane: e para p\u00ebr ngjyr\u00ebn e kuqe, e dyta p\u00ebr t\u00eb gjelbr\u00ebn dhe e fundit p\u00ebr t\u00eb azul\u00ebn.<\/p>\n

Do ta quajm\u00eb secil\u00ebn pik\u00eb n\u00eb k\u00ebt\u00eb matric\u00eb piksel (elementi i pamjes). Secili piksel p\u00ebrmban informacion mbi intensitetin (zakonisht n\u00eb form\u00ebn e nj\u00eb vler\u00eb numerike) t\u00eb secil\u00ebs ngjyr\u00eb. P\u00ebr shembull,
\n\"Si<\/a><\/noindex>
\nnj\u00eb piksel i kuq do t\u00eb thot\u00eb q\u00eb n\u00eb t\u00eb ka 0 ngjyr\u00eb t\u00eb gjelb\u00ebr, 0 ngjyr\u00eb t\u00eb azul dhe maksimumin e ngjyr\u00ebs s\u00eb kuqe.<\/b> Nj\u00eb piksel me ngjyr\u00eb roz\u00eb mund t\u00eb formohet duke p\u00ebrdorur nj\u00eb kombinim t\u00eb tre ngjyrave. Duke p\u00ebrdorur diapazonin numerik nga 0 n\u00eb 255, nj\u00eb piksel roz\u00eb p\u00ebrcaktohet si<\/b> E kuqe = 255 E gjelb\u00ebr = 192<\/b>, E azul = 203<\/b> dhe Artikulli \u00ebsht\u00eb publikuar me mb\u00ebshtetje nga kompania EDISON.<\/b>.<\/a><\/noindex><\/p>\n

\"Si<\/a><\/noindex>

\nNe zhvillojm\u00eb<\/p>\n

aplikacione p\u00ebr mbik\u00ebqyrjen video, video streaming video e regjistruar n\u00eb sall\u00ebn e kirurgjis\u00eb<\/a><\/noindex>, si dhe merremi me M\u00ebnyra alternative p\u00ebr kodimin e imazheve me ngjyra<\/a><\/noindex>.<\/p><\/blockquote>\n

P\u00ebr t\u00eb p\u00ebrfaq\u00ebsuar ngjyrat nga t\u00eb cilat p\u00ebrb\u00ebhet pamja, ka shum\u00eb modele t\u00eb tjera. P\u00ebr shembull, mund t\u00eb p\u00ebrdorim nj\u00eb palet\u00eb indeksuese, ku k\u00ebrkohet vet\u00ebm nj\u00eb bajt p\u00ebr t\u00eb p\u00ebrfaq\u00ebsuar secilin piksel, n\u00eb vend t\u00eb treve q\u00eb k\u00ebrkohen p\u00ebr modelin RGB. N\u00eb nj\u00eb model t\u00eb till\u00eb, mund t\u00eb p\u00ebrdorim nj\u00eb matric\u00eb 2D n\u00eb vend t\u00eb nj\u00eb matrice 3D p\u00ebr t\u00eb p\u00ebrfaq\u00ebsuar \u00e7do ngjyr\u00eb. Kjo kursen hap\u00ebsir\u00ebn memorie, por ofron nj\u00eb gam\u00eb m\u00eb t\u00eb vog\u00ebl ngjyrash.<\/h3>\n

\nRGB<\/p>\n

\"Si
\n<\/p>\n

P\u00ebr shembull, shikoni imazhin m\u00eb posht\u00eb. Nj\u00eb fytyr\u00eb \u00ebsht\u00eb plot\u00ebsisht e ngjyrosur. T\u00eb tjerat jan\u00eb planet e kuqe, t\u00eb gjelbra dhe t\u00eb azul (intensiteti p\u00ebrkat\u00ebs i ngjyrave \u00ebsht\u00eb treguar n\u00eb nuancat e gri).<\/h2>\n

Shohim se nuancat e kuqe n\u00eb origjin\u00eb do t\u00eb jen\u00eb n\u00eb t\u00eb nj\u00ebjtat vende ku v\u00ebrehen pjes\u00ebt m\u00eb t\u00eb ndritshme t\u00eb fytyr\u00ebs s\u00eb dyt\u00eb. Nd\u00ebrsa kontributi i ngjyr\u00ebs s\u00eb azul\u00eb zakonisht mund t\u00eb shihet vet\u00ebm n\u00eb syt\u00eb e Mario (fytyra e fundit) dhe element\u00ebt e veshjeve t\u00eb tij. Vini re se ku t\u00eb tri planet ngjyr\u00ebs kontribuojn\u00eb m\u00eb pak (pjes\u00ebt m\u00eb t\u00eb err\u00ebta t\u00eb imazheve) \u2014 k\u00ebto jan\u00eb mustaqet e Mario.<\/p>\n

\"Si
\n
\nV\u00ebrejtim se nuancat e kuqe n\u00eb origjinal do t\u00eb jen\u00eb n\u00eb t\u00eb nj\u00ebjtat vende ku v\u00ebrehen pjes\u00ebt m\u00eb t\u00eb ndritshme t\u00eb t\u00eb dytit. Nd\u00ebrsa kontributi i ngjyr\u00ebs blu mund t\u00eb shihet kryesisht vet\u00ebm n\u00eb syt\u00eb e Mario (fytyra e fundit) dhe elementet e veshjeve t\u00eb tij. Kujdesi p\u00ebr vendin ku tre planeshngjyrash kontribuojn\u00eb m\u00eb pak (pjes\u00ebt m\u00eb t\u00eb err\u00ebta t\u00eb imazheve) \u2014 \u00ebsht\u00eb n\u00eb mustak\u00ebt e Mario.<\/p>\n

P\u00ebr t\u00eb ruajtur intensitetin e \u00e7do ngjyre k\u00ebrkohet nj\u00eb sasi e caktuar bit\u00ebsh \u2013 kjo sasi quhet thell\u00ebsia e bitit<\/b>. Le t\u00eb themi se shpenzohen 8 bit (duke e marr\u00eb nga vlera nga 0 n\u00eb 255) p\u00ebr nj\u00eb plan t\u00eb vet\u00ebm ngjyre. At\u00ebher\u00eb kemi nj\u00eb thell\u00ebsi ngjyrash prej 24 bit\u00ebsh (8 bit * 3 plane R\/G\/B).<\/p>\n

Nj\u00eb tjet\u00ebr pron\u00eb e imazhit \u00ebsht\u00eb rezolucioni<\/b>, i cili p\u00ebrfaq\u00ebson numrin e piksel\u00ebve n\u00eb nj\u00eb dimension. Shpesh sh\u00ebnohet si gjer\u00ebsi \u00d7 lart\u00ebsi<\/b>, si\u00e7 ilustrohet m\u00eb posht\u00eb n\u00eb shembullin e imazhit 4 me 4.
\n\"Si
\n
\nNj\u00eb tjet\u00ebr pron\u00eb, me t\u00eb cil\u00ebn kemi t\u00eb b\u00ebjm\u00eb gjat\u00eb pun\u00ebs me imazhe\/video \u00ebsht\u00eb raporti i aspektit<\/b>, q\u00eb p\u00ebrshkruan marr\u00ebdh\u00ebnien proporcionale standarde mes gjer\u00ebsi dhe lart\u00ebsi t\u00eb imazhit ose piksel\u00ebve.<\/p>\n

Kur thuhet se nj\u00eb film ose imazh ka madh\u00ebsin\u00eb 16 me 9, zakonisht n\u00ebnkuptohet raporti i aspektit t\u00eb ekranit<\/b> (DAR<\/b> \u2014 nga Raporti i Aspektit t\u00eb Ekranit<\/i>). Megjithat\u00eb ndonj\u00ebher\u00eb mund t\u00eb ket\u00eb forma t\u00eb ndryshme piksel\u00ebsh individual\u00eb \u2013 n\u00eb k\u00ebt\u00eb rast flitet p\u00ebr raportin e piksel\u00ebve<\/b> (PAR<\/b> \u2014 nga Raporti i Aspektit t\u00eb Piksel\u00ebve<\/i>).<\/p>\n

\"Si
\n
\n\"Si<\/p>\n

K\u00ebshill\u00eb p\u00ebr sht\u00ebpiaket: DVD<\/b> p\u00ebrputhet me DAR 4 me 3<\/b><\/p>\n

Megjithat\u00eb, rezolucioni real i DVD-s\u00eb \u00ebsht\u00eb 704\u00d7480, megjithat\u00eb ruan raportin e aspektit 4:3, pasi PAR ka vler\u00ebn 10:11 (704\u00d710 \/ 480\u00d711).<\/p><\/blockquote>\n

\nDhe, n\u00eb fund, mund t\u00eb p\u00ebrcaktojm\u00eb video<\/b> si nj\u00eb sekvenc\u00eb prej n<\/b> kadrash p\u00ebr nj\u00eb periudh\u00eb koh\u00ebs<\/b>, e cila mund t\u00eb merret si nj\u00eb dimension shtes\u00eb. At\u00ebher\u00eb \u2013 kjo \u00ebsht\u00eb frekuenca e kadrave ose numri i kadrave p\u00ebr sekond\u00eb ( n<\/b> FPSKadrat p\u00ebr Sekond\u00eb<\/b> \u2014 nga Numri i bit\u00ebve p\u00ebr sekond\u00eb q\u00eb k\u00ebrkohet p\u00ebr t\u00eb shfaqur video \u00ebsht\u00eb<\/i>).<\/p>\n

\"Si
\n
\nshpejt\u00ebsia e transmetimit bit rate<\/b> \u2014 bit rate = gjer\u00ebsi * lart\u00ebsi * thell\u00ebsi bit\u00ebsh * frekuenca e kadrave<\/b>.<\/p>\n

P\u00ebr shembull, p\u00ebr video me 30 kadrash n\u00eb sekond\u00eb, 24 bit\u00eb p\u00ebr piksel, me rezolucion 480\u00d7240, do t\u00eb k\u00ebrkohen 82,944,000 bit p\u00ebr sekond\u00eb ose 82,944 Mbit\/s (30x480x240x24) \u2013 por kjo \u00ebsht\u00eb n\u00ebse nuk p\u00ebrdoren ndonj\u00eb metod\u00eb kompresimi.<\/p><\/blockquote>\n

\nN\u00ebse shpejt\u00ebsia e transmetimit<\/p>\n

\u00ebsht\u00eb pothuajse konstante , at\u00ebher\u00eb quhet<\/i>shpejt\u00ebsi konstante transmetimi CBR<\/b> (shpejt\u00ebsi konstante bit\u00ebsh<\/b> \u2014 nga ). Por gjithashtu mund t\u00eb variroj\u00eb, n\u00eb k\u00ebt\u00eb rast quhet<\/i>shpejt\u00ebsi variabile transmetimi VBR<\/b> (shpejt\u00ebsi variabile bit\u00ebsh<\/b> \u2014 nga Ky grafikon tregon nj\u00eb VBR t\u00eb kufizuar, kur nuk shpenzohen shum\u00eb bit\u00eb n\u00eb rastin e nj\u00eb kadri plot\u00ebsisht t\u00eb err\u00ebt.<\/i>).<\/p>\n

Fillimisht inxhinier\u00ebt zhvilluan nj\u00eb metod\u00eb p\u00ebr t\u00eb dyfishuar frekuenc\u00ebn e perceptuar t\u00eb kadrave t\u00eb video ekranit pa p\u00ebrdorur band\u00eb shtes\u00eb. Ky m\u00ebnyr\u00eb njihet si<\/p>\n

\"Si
\n
\nvideo me nd\u00ebrprerje video e nd\u00ebrprer\u00eb<\/b>; n\u00eb thelb, ai d\u00ebrgon gjysm\u00ebn e ekranit n\u00eb \"fotografin\u00eb\" e par\u00eb, dhe gjysm\u00ebn tjet\u00ebr n\u00eb \"fotografin\u00eb\" e ardhshme.<\/p>\n

Aktualisht, vizualizimi i skenave kryesisht ndodh duke p\u00ebrdorur teknologjin\u00eb e skanimit progresiv<\/b>. Kjo \u00ebsht\u00eb nj\u00eb m\u00ebnyr\u00eb p\u00ebr t\u00eb shfaqur, ruajtur ose transmetuar imazhe n\u00eb l\u00ebvizje, ku t\u00eb gjitha linjat e \u00e7do fotogrami vizatohen rradhazi.<\/p>\n

\"Si
\n
\nE k\u00ebshtu! Tani dim\u00eb si paraqitet imazhi n\u00eb form\u00eb digjitale, si jan\u00eb strukturuar ngjyrat e tij, sa bit n\u00eb sekond\u00eb shpenzojm\u00eb p\u00ebr t\u00eb treguar video, n\u00ebse shpejt\u00ebsia e transmetimit \u00ebsht\u00eb e q\u00ebndrueshme (CBR) ose variabile (VBR). Jemi njoftuar me rezolut\u00ebn e caktuar duke p\u00ebrdorur frekuenc\u00ebn e caktuar t\u00eb fotogram\u00ebve, si dhe me shum\u00eb terma t\u00eb tjer\u00eb, t\u00eb till\u00eb si video me skanimin fushor, PAR dhe disa t\u00eb tjera.<\/p>\n

Eliminimi i tepric\u00ebs<\/h2>\n

\nDihet se video pa kompresim nuk mund t\u00eb p\u00ebrdoret normalisht. Nj\u00eb video or\u00ebsore me rezolut\u00eb 720p dhe frekuenc\u00eb 30 fotogram\u00eb n\u00eb sekond\u00eb do t\u00eb zinte 278 GB. Arrijm\u00eb n\u00eb k\u00ebt\u00eb vler\u00eb duke shum\u00ebzuar 1280 x 720 x 24 x 30 x 3600 (gjer\u00ebsia, altura, bit\u00ebt p\u00ebr piksel, FPS dhe koha n\u00eb sekonda).<\/p>\n

P\u00ebrdorimi algoritme kompresimi pa humbje<\/b>, si DEFLATE (e p\u00ebrdorur n\u00eb PKZIP, Gzip dhe PNG), nuk do t\u00eb jap\u00eb nj\u00eb tkurrje t\u00eb mjaftueshme t\u00eb shpejt\u00ebsis\u00eb s\u00eb nevojshme t\u00eb transmetimit. Duhet t\u00eb k\u00ebrkojm\u00eb m\u00ebnyra t\u00eb tjera p\u00ebr kompresimin e videos.<\/p>\n

P\u00ebr k\u00ebt\u00eb, mund t\u00eb p\u00ebrdorim ve\u00e7orit\u00eb e shikimit ton\u00eb. Ne i dallojm\u00eb m\u00eb mir\u00eb ndri\u00e7imin se sa ngjyrat. Videoja \u00ebsht\u00eb nj\u00eb grup i imazheve t\u00eb vazhdueshme, q\u00eb rip\u00ebrs\u00ebriten me kalimin e koh\u00ebs. Ndryshimet midis fotograve fqinj t\u00eb nj\u00eb skene jan\u00eb t\u00eb vogla. P\u00ebrve\u00e7 k\u00ebsaj, \u00e7do fotogram p\u00ebrmban shum\u00eb zona, q\u00eb p\u00ebrdorin t\u00eb nj\u00ebjt\u00ebn (ose ngjyr\u00eb t\u00eb ngjashme).<\/p>\n

Ngjyra, ndri\u00e7imi dhe syt\u00eb tan\u00eb<\/h2>\n

\nSyt\u00eb tan\u00eb jan\u00eb m\u00eb t\u00eb ndjesh\u00ebm ndaj ndri\u00e7imit sesa ndaj ngjyr\u00ebs. Mund t\u00eb verifikoni k\u00ebt\u00eb vet\u00eb, duke e par\u00eb k\u00ebt\u00eb imazh.<\/p>\n

\"Si<\/p>\n

N\u00ebse nuk e shihni se n\u00eb gjysm\u00ebn e majt\u00eb t\u00eb imazhit ngjyrat e katror\u00ebve A<\/b> dhe B<\/b> n\u00eb t\u00eb v\u00ebrtet\u00eb jan\u00eb t\u00eb nj\u00ebjta, at\u00ebher\u00eb \u00ebsht\u00eb normale. Truri yn\u00eb na b\u00ebn t\u00eb p\u00ebrqendrohemi m\u00eb shum\u00eb te ndri\u00e7imi sesa te ngjyra. Nga ana e djatht\u00eb, midis katror\u00ebve t\u00eb sh\u00ebnuar ka nj\u00eb lidhje t\u00eb nj\u00ebjt\u00eb ngjyre \u2014 k\u00ebshtu q\u00eb ne (dmth. truri yn\u00eb) leht\u00eb e p\u00ebrcaktojm\u00eb se, n\u00eb t\u00eb v\u00ebrtet\u00eb, atje \u00ebsht\u00eb t\u00eb nj\u00ebjt\u00ebn ngjyr\u00eb.<\/p>\n

Le t\u00eb shikojm\u00eb (thjesht) se si funksionojn\u00eb syt\u00eb tan\u00eb. Syri \u00ebsht\u00eb nj\u00eb organ kompleks, i p\u00ebrb\u00ebr\u00eb nga shum\u00eb pjes\u00eb. Megjithat\u00eb, ajo q\u00eb na intereson m\u00eb shum\u00eb jan\u00eb konihet dhe shufrat. Syri p\u00ebrmban rreth 120 milion shufra dhe 6 milion koni.<\/p>\n

T\u00eb shqyrtojm\u00eb perceptimin e ngjyr\u00ebs dhe ndri\u00e7imit si funksione t\u00eb ve\u00e7anta t\u00eb caktuara nga pjes\u00ebt e caktuara t\u00eb syrit (n\u00eb t\u00eb v\u00ebrtet\u00eb, gj\u00ebrat jan\u00eb pak m\u00eb t\u00eb komplikuara, por ne do ta thjeshtojm\u00eb). Qelizat e shufrave, kryesisht, jan\u00eb p\u00ebrgjegj\u00ebse p\u00ebr ndri\u00e7imin, nd\u00ebrsa qelizat e konihet jan\u00eb p\u00ebrgjegj\u00ebse p\u00ebr ngjyr\u00ebn. Konihet ndahen n\u00eb tre tipe, sipas pigmentit q\u00eb p\u00ebrmbajn\u00eb: S-koni (ngjyr\u00eb e kalt\u00ebr), M-koni (ngjyr\u00eb e gjelb\u00ebr) dhe L-koni (ngjyr\u00eb e kuqe).<\/p>\n

Duke pasur parasysh se ne kemi shum\u00eb m\u00eb shum\u00eb shufra (ndri\u00e7im) sesa koni (ngjyra), mund t\u00eb arrijm\u00eb n\u00eb p\u00ebrfundimin se ne jemi m\u00eb n\u00eb gjendje t\u00eb dallojm\u00eb kalimet midis err\u00ebsir\u00ebs dhe drit\u00ebs, sesa ngjyrat.<\/p>\n

\"Si
\n<\/p>\n

Funksionet e ndjeshm\u00ebris\u00eb ndaj kontrastit<\/h2>\n

\nK\u00ebrkuesit n\u00eb psikologjin\u00eb eksperimentale dhe shum\u00eb fusha t\u00eb tjera kan\u00eb zhvilluar shum\u00eb teori mbi shikimin e njeriut. Nj\u00ebra prej tyre quhet funksionet e ndjeshm\u00ebris\u00eb ndaj kontrastit<\/b>. Ato lidhen me ndri\u00e7imin hap\u00ebsinor dhe temporal. N\u00eb rrafsh t\u00eb shkurtra, b\u00ebhet fjal\u00eb p\u00ebr numrin e ndryshimeve q\u00eb duhen b\u00ebr\u00eb p\u00ebrpara se v\u00ebzhguesi t'i v\u00ebrej\u00eb ato. Vini re shum\u00ebsin e fjal\u00ebs 'funksion'. Kjo lidhet me faktin se mund t\u00eb masim funksionet e ndjeshm\u00ebris\u00eb ndaj kontrastit jo vet\u00ebm p\u00ebr nj\u00eb imazh bardh e zi, por edhe p\u00ebr nj\u00eb imazh me ngjyra. Rezultatet e k\u00ebtyre eksperimenteve tregojn\u00eb se n\u00eb shumic\u00ebn e rasteve syt\u00eb tan\u00eb jan\u00eb m\u00eb t\u00eb ndjesh\u00ebm ndaj ndri\u00e7imit sesa ndaj ngjyr\u00ebs.<\/p><\/blockquote>\n

Duke ditur se jemi m\u00eb t\u00eb ndjesh\u00ebm ndaj ndri\u00e7imit t\u00eb imazhit, mund t\u00eb p\u00ebrpiqemi ta p\u00ebrdorim k\u00ebt\u00eb fakt.<\/p>\n

Modeloja e ngjyr\u00ebs<\/h2>\n

\nNe paksa e kuptuam se si funksionojm\u00eb me imazhe me ngjyra, duke p\u00ebrdorur skem\u00ebn RGB. Ka edhe modele t\u00eb tjera. Ekziston nj\u00eb model q\u00eb ndan ndri\u00e7imin nga ngjyra dhe ai njihet si YCbCr<\/b>. P\u00ebr pazar, ka edhe modele t\u00eb tjera q\u00eb b\u00ebjn\u00eb ndarjen e ngjashme, por ne do t\u00eb shqyrtojm\u00eb vet\u00ebm k\u00ebt\u00eb.<\/p>\n

N\u00eb k\u00ebt\u00eb model ngjyrash Y<\/b> \u2014 \u00ebsht\u00eb paraqitja e ndri\u00e7imit, si dhe p\u00ebrdoren dy kanale ngjyrash: Cb<\/b> (blu e ngopur) dhe Cr<\/b> (e kuqe e ngopur). YCbCr mund t\u00eb marr\u00ebhet nga RGB, ashtu si\u00e7 \u00ebsht\u00eb e mundur t\u00eb b\u00ebhet edhe transformimi i kund\u00ebrt. Duke p\u00ebrdorur k\u00ebt\u00eb model, ne mund t\u00eb krijojm\u00eb imazhe n\u00eb ngjyra t\u00eb plota, si\u00e7 e shohim m\u00eb posht\u00eb:<\/p>\n

\"Si
\n<\/p>\n

Transformimi nd\u00ebrmjet YCbCr dhe RGB<\/h2>\n

\nDisa mund t\u00eb kund\u00ebrshtojn\u00eb: si \u00ebsht\u00eb e mundur t\u00eb marrim t\u00eb gjitha ngjyrat, n\u00ebse nuk p\u00ebrdorim t\u00eb gjelbr\u00ebn?<\/p>\n

P\u00ebr t\u00eb p\u00ebrgjigjur n\u00eb k\u00ebt\u00eb pyetje, do t\u00eb transformojm\u00eb RGB n\u00eb YCbCr. Do t\u00eb p\u00ebrdorim koeficient\u00ebt e pranuar n\u00eb standardin BT.601<\/b>, i cili \u00ebsht\u00eb rekomanduar nga nj\u00ebsi e ITU-R<\/b>. Kjo nj\u00ebsi p\u00ebrcakton standardet p\u00ebr video digjitale. P\u00ebr shembull: \u00e7far\u00eb \u00ebsht\u00eb 4K? Si duhet t\u00eb jet\u00eb frekuenca e kadrave, rezolucioni, modeli i ngjyrave?<\/p>\n

S\u00eb pari, do t\u00eb llogarisim ndri\u00e7imin. Do t\u00eb p\u00ebrdorim konstantet e propozuara nga ITU dhe do t\u00eb z\u00ebvend\u00ebsojm\u00eb vlerat RGB.<\/p>\n

Y<\/b> = 0.299R<\/b> + 0.587G<\/b> + 0.114B<\/b> <\/p>\n

Pasi t\u00eb kemi marr\u00eb ndri\u00e7imin, do t\u00eb ndalim ngjyr\u00ebn blu dhe t\u00eb kuqe:<\/p>\n

Cb<\/b> = 0.564(B<\/b> \u2014 Y<\/b>)<\/p>\n

Cr<\/b> = 0.713(R<\/b> \u2014 Y<\/b>) <\/p>\n

Dhe ne gjithashtu mund t\u00eb transformojm\u00eb p\u00ebrs\u00ebri dhe madje t\u00eb marrim t\u00eb gjelbr\u00ebn me ndihm\u00ebn e YCbCr:<\/p>\n

R<\/b> = Y<\/b> + 1.402Cr<\/b><\/p>\n

B<\/b> = Y<\/b> + 1.772Cb<\/b><\/p>\n

G<\/b> = Y<\/b> \u2014 0.344Cb<\/b> \u2014 0.714Cr<\/b><\/p>\n

N\u00eb p\u00ebrgjith\u00ebsi, nd\u00ebrfaqet (monitor\u00ebt, televizor\u00ebt, ekranet etj.) p\u00ebrdorin vet\u00ebm modelin RGB. Por ky model mund t\u00eb organizohet n\u00eb m\u00ebnyra t\u00eb ndryshme:<\/p>\n

\"Si
\n<\/p>\n

N\u00ebnmostrimi i ngjyrave<\/h2>\n

\nMe nj\u00eb imazh t\u00eb paraqitur si nj\u00eb kombinim t\u00eb ndri\u00e7imit dhe ngjyrosjes, ne mund t\u00eb p\u00ebrdorim ndjeshm\u00ebrin\u00eb m\u00eb t\u00eb lart\u00eb t\u00eb sistemit ton\u00eb vizual ndaj ndri\u00e7imit sesa ndaj ngjyr\u00ebs, n\u00ebse hiqnim informacionin selektivisht. Subdiskretizimi i ngjyrave \u00ebsht\u00eb nj\u00eb metod\u00eb kodimi e imazheve, duke p\u00ebrdorur nj\u00eb rezolucion m\u00eb t\u00eb ul\u00ebt p\u00ebr ngjyrosjen se sa p\u00ebr ndri\u00e7imin.<\/p>\n

\"Si<\/p>\n

Sa e lejuar \u00ebsht\u00eb t\u00eb zvog\u00eblohet rezolucioni i ngjyrave?! Eksplorohet se tani jan\u00eb disa skema q\u00eb p\u00ebrshkruajn\u00eb si t\u00eb trajtojm\u00eb rezolucionin dhe bashkimin (Ngjyra p\u00ebrfundimtare = Y + Cb + Cr).<\/p>\n

K\u00ebto skema jan\u00eb t\u00eb njohura si sistemet e subdiskretizimit<\/b> dhe shprehen n\u00eb form\u00ebn e nj\u00eb raporti 3:1 \u2014 a<\/b>:x<\/b>:y<\/b>, i cili p\u00ebrcakton numrin e mostrave t\u00eb sinjaleve t\u00eb ndri\u00e7imit dhe ngjyr\u00ebs.<\/p>\n

a<\/b> \u2014 standard i mostr\u00ebs horizontale (zakonisht barazohet me 4)
\nx<\/b> \u2014 numri i mostrave t\u00eb ngjyrosjes n\u00eb rreshtin e par\u00eb t\u00eb piksel\u00ebve (rezolucioni horizontal n\u00eb lidhje me a<\/b>)
\ny<\/b> \u2014 numri i ndryshimeve t\u00eb mostrave t\u00eb ngjyrosjes midis rreshtit t\u00eb par\u00eb dhe atij t\u00eb dyt\u00eb t\u00eb piksel\u00ebve.<\/p>\n

P\u00ebrjashtimi \u00ebsht\u00eb 4<\/b>:1<\/b>:0<\/b>, duke siguruar nj\u00eb mostr\u00eb ngjyrosjeje n\u00eb secilin bllok t\u00eb rezolucionit t\u00eb ndri\u00e7imit 4 me 4.<\/p><\/blockquote>\n

Skemat e p\u00ebrgjithshme t\u00eb p\u00ebrdorura n\u00eb kodek\u00ebt modern\u00eb:<\/p>\n